Buggy code:
public class ManifestHeaderProcessor { public static final String NESTED_FILTER_ATTRIBUTE = "org.apache.aries.application.filter.attribute" ; private static final Pattern FILTER_ATTR = Pattern . compile ( "(\\(!)?\\((.*?)([<>]?=)(.*?)\\)\\)?" ) ; private static final String LESS_EQ_OP = "<=" ; private static final String GREATER_EQ_OP = ">=" ; public static class NameValuePair < N , V > { private N name ; private V value ; public NameValuePair ( N name , V value ) { } public N getName ( ) { } public void setName ( N name ) { } public V getValue ( ) { } public void setValue ( V value ) { } @ Override public String toString ( ) { return ( ( ( "{" + ( name . toString ( ) ) ) + "::" ) + ( value . toString ( ) ) ) + "}" ; } @ Override public int hashCode ( ) { } @ Override public boolean equals ( Object obj ) { } } public static interface NameValueCollection < N , V > { public void addToCollection ( N n , V v ) { } } public static class NameValueMap < N , V > extends HashMap < N , V > implements Map < N , V > , ManifestHeaderProcessor . NameValueCollection < N , V > { public void addToCollection ( N n , V v ) { } @ Override public String toString ( ) { <START_BUG> StringBuffer sb = new StringBuffer ( ) ; <END_BUG> sb . append ( "{" ) ; boolean first = true ; for ( Map . Entry < N , V > entry : this . entrySet ( ) ) { if ( ! first ) sb . append ( "," ) ; first = false ; sb . append ( ( ( ( entry . getKey ( ) ) + "->" ) + ( entry . getValue ( ) ) ) ) ; } sb . append ( "}" ) ; return sb . toString ( ) ; } } public static class NameValueList < N , V > extends ArrayList < ManifestHeaderProcessor . NameValuePair < N , V > > implements List < ManifestHeaderProcessor . NameValuePair < N , V > > , ManifestHeaderProcessor . NameValueCollection < N , V > { public void addToCollection ( N n , V v ) { } @ Override public String toString ( ) { StringBuffer sb = new StringBuffer ( ) ; sb . append ( "{" ) ; boolean first = true ; for ( ManifestHeaderProcessor . NameValuePair < N , V > nvp : this ) { if ( ! first ) sb . append ( "," ) ; first = false ; sb . append ( nvp . toString ( ) ) ; } sb . append ( "}" ) ; return sb . toString ( ) ; } } public static List < String > split ( String value , String delimiter ) { } private static List < ManifestHeaderProcessor . NameValuePair < String , ManifestHeaderProcessor . NameValueMap < String , String > > > genericNameWithNameValuePairProcess ( String s ) { } private static ManifestHeaderProcessor . NameValueMap < String , String > genericNameValueProcess ( String s ) { } private static void genericImportExportProcess ( ManifestHeaderProcessor . NameValueCollection < String , ManifestHeaderProcessor . NameValueMap < String , String > > out , String s ) { } public static List < ManifestHeaderProcessor . NameValuePair < String , ManifestHeaderProcessor . NameValueMap < String , String > > > parseExportString ( String s ) { } public static List < ManifestHeaderProcessor . NameValuePair < String , ManifestHeaderProcessor . NameValueMap < String , String > > > parseExportList ( List < String > list ) { } public static Map < String , ManifestHeaderProcessor . NameValueMap < String , String > > parseImportString ( String s ) { } public static ManifestHeaderProcessor . NameValuePair < String , ManifestHeaderProcessor . NameValueMap < String , String > > parseBundleSymbolicName ( String s ) { } public static VersionRange parseVersionRange ( String s ) throws IllegalArgumentException { } public static VersionRange parseVersionRange ( String s , boolean exactVersion ) throws IllegalArgumentException { } public static String generateFilter ( Map < String , String > attribs ) { } public static String generateFilter ( String type , String name , Map < String , String > attribs ) { } private static Map < String , String > parseFilterList ( String filter ) { } public static Map < String , String > parseFilter ( String filter ) { } public static Content parseContent ( String bundleSymbolicName , String versionRange ) { } public static Content parseContent ( String contentName , ManifestHeaderProcessor . NameValueMap < String , String > nameValueMap ) { } }

Fix:
StringBuilder sb = new StringBuilder ( ) ;